The characters are a bit hard to read against the background because the background has a pretty wide value range. Using a wide range of values as a stand-alone piece, but leads to clarity problems for pieces used as backgrounds, especially when the foreground (the characters) are mostly midtones.
Your scenery fades towards a dark colour the further away it goes, yet the sky is light. This causes the horizon to be the most high-contrast, attention-grabbing thing rather than anything in the foreground, and it looks a bit strange, since generally things fade towards the sky-colour in the distance.